WASHINGTON — Overruling his air force in a 1983 arms deal, then President Ferdinand Marcos of the Philippines decreed that 19 helicopters be bought from a U.S. company represented by former Secretary of State Alexander Haig and a Manila businessman reputed to be a Marcos ''crony.''

The $63.5 million deal was ''railroaded'' by Marcos and Gen. Fabian Ver, the armed forces chief of staff, said a former Philippine military procurement official.

Marcos ordered his air force to buy Sikorsky helicopters from United Technologies Corp. of Hartford, Conn., even though the air force commander and other officers had recommended buying less expensive craft manufactured by Bell Helicopter